1. Field of the Invention
The present invention relates to a process for the production of a sodium-filled valve in which the sodium is introduced into a hollow valve stem through a filling bore of relatively large diameter and which is sealed through a plug and/or usual welding.
2. Discussion of the Prior Art
The purpose of such a sodium filling of valves, particularly of such fillings for piston engines, is to provide an improved heat transfer from the thermally highest loaded valve head as a result of the extraordinarily superior heat conductivity of the sodium. However, due to the high thermal expansion of the sodium, the hollow-bored valve stem cannot be completely filled with sodium, but only up to about 80%. The remaining empty space within the hollow valve stem contains ambient air which, during the operation of the valve, leads to the frothing and corrosion of the sodium; thereby leading to an unstable heat conduction, as well as adversely affecting the heat transfer.